1. Field of the Invention
The present invention relates to kilns for waste disposal and in particular to means for use in municipal waste incinerators for inhibiting corrosion and erosion within the structure.
2. The Prior Art Environment
Water cooled kilns for waste disposal are well known, and an important constructional configuration which has found a great deal of use, particularly in municipal solid waste applications, is the kiln of Harris and O'Connor disclosed in U.S. Pat. No. 3,822,651. This particular kiln has become known as the Westinghouse-O'Connor Combustor, or WOCC for short. A WOCC kiln, which may also be referred to as a rotary combustor, is formed from a number of water pipes which are interconnected by perforated strips or web sections, all welded together to present a cylinder defining a combustion chamber. The perforations in the strips or web sections permit air to enter the combustion chamber radially through the cylinder wall, and provide air jets for the burning waste in the interior of the cylinder.
The '651 patent, cited above, illustrates the overall configuration of the combustion system, and the entirety of the disclosure of said '651 patent is hereby specifically incorporated herein by reference. During operation of the WOCC illustrated in the '651 patent, when the cylinder rotates about its slightly inclined axis, the unburned, partially or completely burned solid waste tumbles and repeatedly rests, at least for finite periods of time, on the bottom of the cylinder. The plates or webs separating the water pipes are alternatively exposed to solid waste in various stages of oxidation ranging from a wet unburned condition to a glowing mass. The web sections tend to corrode, with the greatest wastage in the vicinity of the air emission holes, as a result of the combined effects of corrosion caused by chlorine accelerated oxidation and erosion at high temperature. In fact, wastage may be so high that web replacement becomes necessary after only a few years of operation.